Abstract

Objectives
School meal programs in South Korea are a major public nutrition service and an important part of student diets. Although previous National Education Information System (NEIS)-based studies have described frequently served menu items and annual trends, nationwide evidence on how school lunch menus differ seasonally remains limited. Thus, in this exploratory study, we aimed to analyze summer–winter differences in frequently served items in South Korean elementary, middle, and high schools.
Methods
Nationwide school lunch records from 2023 to 2025 were obtained from the National School Meal Information application programming interface (API). Lunch meal units served in elementary, middle, and high schools were analyzed. The final dataset comprised 1,200,000 meal units. Menu items were classified into six categories: rice/noodles, soups/stews, kimchi, main dishes, side dishes, and desserts. In each category, items frequently served in summer and winter were identified, and seasonal differences were quantified using a seasonal gap index and z-tests.
Results
Seasonal variation was highest in kimchi and desserts. Among the top items, 25/26 kimchi items and 27/30 dessert items showed significant seasonal differences. In desserts, watermelon, oriental melon, and ice cream were strongly summer-dominant, whereas apple, strawberry, and sweet persimmon were winter-dominant. In kimchi, young summer radish kimchi and cucumber kimchi were summer-dominant, whereas diced radish kimchi and napa cabbage kimchi were winter-dominant. Rice/noodles, soups/stews, and side dishes showed moderate seasonal variation. Main dishes showed the lowest degree of seasonal variation, with all-time popular items displaying minimal variation.
Conclusion
Seasonal variation in menu items was concentrated in specific categories rather than evenly distributed across all categories. Item-level analysis revealed that familiar meal structures were maintained overall, whereas specific menu items were seasonally rotated. These findings provide practical evidence for seasonally sensitive school meal planning, particularly in categories with greater seasonal variation.

• Keywords: school meals; foodservice; seasonality; menu patterns; Republic of Korea